1. Field of the Invention
The present invention relates to machines for manufacturing a continuous layer of a fiber material having rotating rolls and, more particularly, to a method of providing an offset for a freely carrying bearing assembly on a roll in a machine for manufacturing a continuous layer of a fiber material.
2. Description of the Related Art
Machines for making fiber materials, such as paper, cardboard and the like, are well known. The fiber material is made in large continuous sheets known as webs. These machines utilize a plurality of rotating rolls or cylinders to move the fiber material web through the various stages of manufacture. The rotating cylinders perform a variety of functions. Generally, subset pluralities of cylinders are grouped into sections with each section performing a different task. An exemplary task in the making of the fiber material is drying in which one or many sections of dryer cylinders are utilized.
During the drying process, the fiber material web is directed through the series of drying cylinders that comprise the section. The drying cylinders are rotating rolls that can be heated to take the moisture away from the fiber material web as the fiber material web is caused to come into contact with an area of the cylinder. Generally these drying cylinders use steam supplied to the interior of the cylinder via attached tubing to heat the cylinder. The cylinder is made from a thermally conductive material such as an appropriate metal. As a result of such heating, the cylinders thermally expand in all directions, but especially along the longitudinal axis about which the roll rotates. The bearings at the ends of the cylinder are seated in housings that are firmly fixed to a support structure.
As the cylinders rotate at a high velocity to move the fiber material web along the fiber making machine, the ends of the cylinders are retained in bearings that must be designed to handle such speeds. Since the rotating cylinders are subject to axial and radial movement and perturbations, the bearings should be adapted to handle same. One type of bearing that can accommodate axial and radial movement is a freely carrying bearing, such as a so-called CARB (Continuous Alignment Roller Bearing) type bearings. Such CARB type bearings are manufactured by AB SKF of The SKF Group. When installing a freely carrying bearing on a cylinder, it is necessary to align the bearing assembly relative to the journal or cylinder axis (also the axis of rotation of the cylinder) in the X, Y and Z directions. Because of the precision at which the cylinder or roll needs to rotate, the more precise the alignment should be between the freely carrying bearings and the cylinder axis.
In an SKF brochure entitled xe2x80x9cThe CARB bearingxe2x80x94a better solution for the front side of drying cylinders,xe2x80x9d publication number 4410/1 E, copyright 1997 by SKF and specifically incorporated herein by reference, sets forth basic mounting instructions and target tolerances or offsets for installation of its CARB type freely carrying bearings. The mounting instructions include: 1) lubricating the mating surfaces (outer surface of journal and inner surface of inner race of bearing); 2) positioning the bearing assembly in the housing and on the shaft; 3) unloading the rollers of the bearing assembly; 4) driving the inner ring of the bearing assembly to a starting position on the journal by applying hydraulic pressure through a hydraulic ring nut; 5) driving the inner ring of the bearing assembly a required distance (SSxc2x15%) up the taper of the journal and waiting a few minutes; 6) bolting the bearing housing to the frame; 7) checking bearing housing alignment; 8) checking that axial displacement (of inner ring relative to outer ring) is within an acceptable range; and, if necessary, 9) adjusting the position of the bearing housing.
Because of the thermal expansion of the cylinder during operation, it is known to utilize the properties of a freely carrying bearing and axially offset the outer ring of the bearing assembly which is attached to the bearing housing relative to the inner ring of the bearing assembly which is affixed to the cylinder journal. Various offset values have been calculated by manufacturers for their particular freely carrying bearings, such as the SKF CARB, relative to thermal expansion of the cylinder.
What is needed in the art, however, is a method of aligning a freely carrying bearing assembly on a cylinder/cylinder journal in a fiber-making machine.
What is also needed is a method of determining and/or positioning an offset between an inner race and outer race of a freely carrying bearing assembly mounted onto a journal of a dryer cylinder in a paper-making machine.
The present invention is a method for aligning a freely carrying bearing assembly on a cylinder of a fiber-making machine. The freely carrying bearing assembly includes an inner race, an outer race, and a plurality of rollers therebetween.
The method comprises determining a desired outer race to inner race offset, determining an existing outer race to inner race offset relative to an alignment plate by utilizing measurements taken through the plurality of measurement slots in the alignment plate, and determining a correction outer race to inner race offset between the determined desired outer race to inner race offset and the determined existing outer race to inner race offset. The bearing is then aligned by axially positioning the seating structure according to any determined correction outer race to inner race offset.
The alignment plate includes an opening for the journal of the cylinder and a plurality of measurement slots radially extending from the opening. Preferably there are four slot positioned at 0xc2x0, 90xc2x0, 180xc2x0, and 270xc2x0. Each required determination according to the present method or measurement of axial length is preferably made from each slot.